You can fill from the top but you will have flooding issues at the beginning.
What I do when I fill from the top is place tape over the holes to help a bit, then as I'm screwing the top cap on, i give it a couple turns and flip the unit upside down. after i'm finished putting the unit together, I'll hold it upside down and blow through the drip tip. this will clear the chamber which will expel through the air intake hole.
2 times max of doing this and you'll be ready to rock
This method just seems like your making problems for yourself? What's wrong with filling via the fill hole? Am I missing something is there some benefit to filling from the top?